A novel class of highly abundant polypeptides with antifungal activity has been detected in cell walls of barley leaves. Similar polypeptides known as thionins occur not only in monocotyledonous but also in various dictoyledonous plants. The leaf‐specific thionins of barley are encoded by a complex multigene family, which consists of at least 50‐100 members per haploid genome. All of these genes are confined to chromosome 6. The toxicity of these thionins for plant pathogenic fungi and the fact that their synthesis can also be triggered by pathogens strongly suggest that thionins are a naturally occurring, inducible plant protein possibly involved in the mechanism of plant defence against microbial infections.

In the autumn large amounts of a major storage protein accumulate in the woody stem of poplar trees. This protein is stored in xylem ray cells during the winter season and is degraded in late spring. The accumulation of this protein is preceded by a dramatic but transient appearance of the corresponding mRNA. Thus, the seasonal change in the mRNA content appears to be a crucial event for the storage of nitrogen in the stem. The amino acid sequence of the storage protein has been deduced from the nucleotide sequence of a full-length cDNA. The cDNA shows a nucleotide sequence similarity of approximately 75% with two published cDNA sequences of poplar which represent transcripts that accumulate systemically in leaves of poplar trees in response to wounding.

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